Skip esxi reimage based on knob in testbed.py
Skip esxi reimage based on knob in testbed.py

New knob added in testbed.py to aviod re-image of esxi server

esxi_hosts = {
    'nodel5' : {
        'ip' : '10.204.217.212',
        'username' : 'root',
        'password' : 'c0ntrail123',
        'cluster' : 'a11a29_blr',
        'datastore' : '/vmfs/volumes/l5-ds',
        'vcenter_server': 'vcenter10',
        'skip_reimage'  : 'true'  >>>>>>>>
        },
For vcenter gateway sanity, we decided not to provision the vcenter side.Hence re-iamge
of esxi server not allowed.

Closes-Bug: #1625513

Change-Id: If6bc7636ffd055c65a340b831e78d6001915f480

Juniper/contrail-fabric-utils,Juniper/contrail-fabric-utils